Wireless communication systems have been implemented in numerous applications such as worldwide television, communication to remote areas, wide area data networks, global personal communications to hand-held portable telephones, broadband voice, video, and data. As the number of applications has increased and the number of users using the applications has increased, processes have been developed to accommodate these increased applications and users. One such process that has been developed is multiplexing.
In multiplexing, multiple signals may be transmitted on a single channel, and many forms of multiplexing have been developed to generate a multiplexed communication signal, including, but not limited to time multiplexing, frequency multiplexing, space multiplexing (e.g., Frequency-Division Multiplexing (FDM), Time-Division Multiplexing (TDM), Space-Division Multiplexing (SDM), Orthogonal Frequency Multiplexing (OFM), Code-Division Multiple Access (CDMA) multiplexing, Wideband CDMA (WCDMA) multiplexing, Time-Division Multiple Access multiplexing, Orthogonal Frequency Multiple Access (OFMA) multiplexing, and Frequency Division Multiple Access multiplexing (FDMA)).
CDMA refers to a form of multiplexing that allows numerous signals to occupy a single transmission channel thereby optimizing the use of available bandwidth. CDMA employs analog-to-digital conversion in combination with spread spectrum signal processing whereby a multiplier combines an information signal, such as speech, with a high-rate digital spreading code. At a transmitter (e.g., a cellular base station), an analog-to-digital converter digitizes the information signal for transmission at a predetermined data rate, and a multiplier varies the digitized signal according to a defined pattern or code. In addition, the transmitter typically performs additional signal processing, such as speech encoding, channel encoding, interleaving, and framing of the digitized signal, prior to transmission. The resulting transmission signal has a relatively wide band with a bandwidth of the spreading code.
Communication systems may at times transmit physical layer control data. For example, in many conventional communication systems using CDMA, a base station transmits a power control message to a mobile communication unit (e.g., cellular phone) to regulate the power output of the cellular phone during communication. In a satellite WCDMA communication system, a framer organizes a transmission into a sequence of frames, and the frames are divided into time slots. For a forward link, each time slot carries a Dedicated Physical Data Channel (DPDCH) and a corresponding Dedicated Physical Control Channel (DPCCH), and the DPCCH carries a power control field and a frame control header that indicates the DPDCH format and data rate. The power control field has two bits that indicate an increase power command or a decrease power command, and the power control field and frame control header are coded together and mapped to a fifteen (15) bit sequence belonging to a family of thirty-two (32) sequences.
For forward traffic communication, a conventional CDMA 2000 communication system periodically overwrites or “punctures” a power control bit into known power control groups (e.g., pre-determined positions within a frame) after interleaving. A “Ø” bit indicates an increase in mean output power level, and a “1” bit indicates a decrease in mean output power level. Upon consideration of the frequency of frames transmitted per second, conventional CDMA 2000 and WCDMA communication systems both dedicate a significant portion of communication bandwidth to the transmission of power control information.
Terrestrial-based communication systems using CDMA 2000 or wideband CDMA typically have relatively fast roundtrip times for communication signals to travel between the base station and the mobile communication unit. The frequent power control messaging (e.g., a power control message transmitted in each frame) in these communication systems permits a tight control of power output during communication. In satellite-based communication systems, the roundtrip times for communication signals traveling between a satellite transponder and a mobile communication unit typically exceed the roundtrip times associated with terrestrial-based communication signals. Within the span of the roundtrip time between the satellite transponder and the mobile communication unit, the CDMA 2000 and wideband CDMA systems transmit several or many power control messages, and this roundtrip time limits the response to such power control messages.
In view of the foregoing, it is desirable to provide a communication system that reduces bandwidth consumption for physical layer control messaging. In addition, it is desirable to provide a method for signaling control information in a communication system that minimally consumes bandwidth. In addition, it is desirable to provide a communication system for transmitting low rate control data that has a substantially wide variety of control content for the control data. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.